Touch screen technology has advanced in recent years such that touch screen technology can be found in many consumer-level devices and applications. For example, banking machines often include a touch-sensitive graphical user interface that allows users to select a function (e.g., withdrawal or deposit) and an amount for withdrawal or deposit. In another example, mobile telephones or mobile media players can include touch screen technology, wherein such technology can be employed in connection with user selection of graphical icons on an interactive interface with the use of a stylus. In still yet another example, some laptop computers are equipped with touch screen technology that allows users to generate signatures, select applications, and perform other tasks with the use of a stylus or their fingers.
The popularity of touch screen technology has increased due to ease of use, particularly for novice computer users. For instance, novice computer users may find it more intuitive to select a graphical icon by hand than to select the icon through use of various menus and a pointing and clicking mechanism, such as a mouse. In currently available systems, users can select, move, modify, or perform other tasks on objects that are visible on a display screen by selecting such objects (e.g., with a stylus or their finger).
A common problem in applications that need three-dimensional interfaces, such as mechanical computer-aided drafting applications, computer game programming applications, animation software, and general three-dimensional user interfaces is that it is difficult to position and orient rigid objects. Unlike objects in a two-dimensional plane, which only have two translational and one rotational degree of freedom, objects in three-dimensional space have three translational and three rotational degrees of freedom.
Some current techniques for manipulating three dimensional objects on a graphical user interface use special hardware interfaces, such as virtual reality gloves, which can be used to grab objects and place them in space. Another example hardware interface is a six degree of freedom input device such as a spaceball. These hardware solutions tend to be relatively expensive. Software-based methods using ordinary mice, trackballs, and keyboards are cheap but inadequate in that users often find three dimensional objects difficult to control when using such software-based methods. That is, the behaviour of the object on the screen is non-intuitive to the point that positioning and orienting a three-dimensional object precisely is extremely difficult.
As indicated above, touch screen technology has become more prevalent, particularly in connection with mobile devices such as portable telephones and portable media players. Many of these touch sensitive display devices include multi-touch functionality, such that a user can utilize multiple members (fingers) to cause objects to act in a particular manner. Conventionally, there is no suitable manner to position and orient a three-dimensional object rendered in a graphical user interface on a multi-touch display surface.